Hi!

I'm considering switching from Dura Ace 7900 to 9000.
I have some old wheelsets which are 10speed and cannot be upgraded to 11. (DA WH78xx 50mm carbon tubs for example )
My question is - will the 9000 work with 7900 10speed sprockets? As far as I get it the spacing between sprockets is the same, on 9000 they just added one more sprocket so the cassete is wider.
So, theoretically, the shifter should work if you limit the deraileur (and of course you'll have one click to much)

Any comments appreciated!

Nope, the cog spacing is not the same.

I think the 9000 spline is the same. If so you could take a 9000 cassette, remove a cog and put it on a 10sp freehub, adding spacers as needed. Not all 9000 cassettes would have a solo cog in the position you'd want to remove.

Shimano has the cassette tech doc:
http://techdocs.shimano.com/media/techd ... 807221.pdf

Well, perhaps J-tek will come out with a ShiftMate model http://jtekengineering.com/shiftmate.php which does the trick, or add Shimano 11 shifting Shimano 10 as a declared capability for an existing model, but I have no particular knowledge that they will. You could ask them though.

Minor derail.

Would a 7900 crank (dura ace SRM) work with 9000?

Can't see why not, so far I've even managed to get 8 speed rings/crankset (campy) work on 11 speed.
Even if manufacturers say it won't work often they mean that it's a bit less than optimal but the statement is made for the sake of sales figures and too many
customers that have questions about combining parts..... (and for the US market to avoid legal issues)

Seems like I'll have to try to put DA7900 whelset on DA9000 bike and see if it works.

Anyway, if I'll have to change all the casetes on my existing wheels thats to expensive.
9000 is nice and promising but buying 2 or 3 DA casetes is a luxury. Maybe its better to wait until ultegra 11 comes out and then go for 11.

According to another thread I have been reading, the answer is 'yes' you can use a 10spd cassette with the 9000 RD and 9000 STI lever

than why buy 9000 if you have still "only" 10 speeds?

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The cog spacing is not the same so it wouldn't work real well. FWIW, Shiomano 10 spacin his 3.95mm while Campy 11 is only 3.8mm. Shimano and Campy 11 both use the the same cog thickness of 1.6mm. If anything, both 11 speed cogs spacing will be the most similar.

A 10 speed cassette would also require a spacer to work on the longer 11 speed cassette body.

Shimano 11sp wheels ship with a spacer for a 10sp cassette. I think it's 1.85mm.

You'd think that the 9000 cable operated derailleur would have an alternate cable clamping position that works for 10sp, like they did on earlier derailleurs. And that the 9000 electronic group would be programmable for 10sp or 11sp. That should be easy.

What i find annoying, no it pixxes me off actually Is that the 11sp Cassettes dont fit the current Shimano 2012 7900 wheel range.

Maybe Shimano will bring out a Freehub body for these wheels? Its one thing splashing out for a new grp set but quite another to make their own wheels obsolete

The current manufacturing and marketing model, especially with the electronic stuff, is to constantly bring NEW and "improved" but not backwards compatible items to your drivetrain.
Think about your cell phones for the past 10 years, how many of them could use the same memory cards or power plugs or anything else? Constantly changed in the name of "progress" whose effect is to make customers buy peripherals over and over again.

The do not want wiring harnesses compatible, they do not want wheels backwards compatible, they want people to buy all new stuff all over again.

My Di2 was supposed to last till eternity, but Madcow already tells me not to hold my breath on shimano supporting it as it has already been supplanted 2+ times in 2 years (ultegra di2 and now 9000 electronic).
As it was only a fraction of shops had the gear to analyze and fix Di2, now most of those no longer will bother with that and move onto the 9000 series diagnostic gear.

This is progress in the digital age, like the evolution from standardized and perfectly functional turntable (which would take any needle) to the CD player, which is improved tweaked and re-released every 6-12 months (better DACs, digital sampling scrubber, etc.)

Disagree with that analogy, for a start phones are consumables that dont last long, are bought on contract and are upgradeable - in the UK - and most importantly dont cost you £1000s to buy in the first place!

A better one would be Cameras - Canon V Nikon, (Campag v shimano) neither company brings out a new body or lense that has a different fit, everything is backward compatable - Shimano 9000 isnt electronic and wheels arnt either.
Imagine if Canon change their mount and all those EF/s lenses wouldnt fit anymore? their sales would fall through the floor.

Campag bought out 11sp and that can still use their older wheelsets (im not expecting 11sp sti to work with 7900 10sp sti) so i dont get why Shimano cant (or wont?)

as i said previously, wheelsets are a major investment, costing as much or more than the grp set - to make their current wheels obsolete is just wrong.

Even Apple provide an adaptor for the new ip5 and existing accesories

Let's not forget that Campy changed their freehub body when they went to 8sp drivetrains (IIRC. It might have been to 9sp but not 100% sure, but it was at some point in the 90s). They obsoleted every hub they had produced before that point. Sometimes design evolution has to give way to a new design parameter entirely. Sure, Shimano probably could have made the 11sp cassette fit existing 10sp bodies, but would the cogs and chain have had to be too thin to be durable? Would folks then be bitching about chains that last only two months, and things like that?

It sucks, but if you want 11sp Shimano, they have decided that in order to make a product that meets their standards of design efficiency and robustness, they had to go to a wider cassette, necessitating a wider hub body. If you don't like it, stick with 10sp Shimano or go to SRAM. Nobody's forcing consumers to buy the new 9000 and 9070 Shimano components.